Page 74 - Mechatronic Systems Modelling and Simulation with HDLs

4

Modelling in Hardware

Description Languages

4.1 Introduction

For hardware description languages (HDL) — as for every other method of describ-
ing a system — the following two questions are raised:

• What can be modelled using this description method?
• What can be achieved using this description?

This is illustrated on the basis of Figure 4.1. On the left-hand side we see the
domains that are significant in our context, which are to be modelled in hardware
description languages. Digital and analogue electronics should be unproblematic
because hardware description languages were originally developed for precisely
this purpose. Question marks stand next to the domains of multibody mechanics,
continuum mechanics and software; the modelling of these domains using hardware
description languages is investigated in this book. Furthermore, some approaches
should be mentioned at this point that attempt to automatically translate further
description forms into hardware description languages. The work of Maillot and
Wendling [246], in which state diagrams are depicted in VHDL, is worth mention-
ing here. Sax et al. [359] transfer MATRIX X descriptions from classical control
technology into VHDL-AMS. Overall, hardware description languages, and in par-
ticular VHDL-AMS, appear to be capable of serving as a general exchange format
for models.
The question remains of what we can undertake using a system model in a
hardware description language. This is shown on the right-hand side of Figure 4.1.
Initially it is possible to specify and design using hardware description languages
with the resulting models being available for documentation purposes in both cases.
Furthermore, such a description can be directly simulated without any intermediate

Mechatronic Systems Georg Pelz
 2003 John Wiley & Sons, Ltd ISBN: 0-470-84979-7